Continuity mistake: When the Samuels are escaping through the window Linda asks them if they're all right, and in the first shot Ed is gripping the line with his right hand while holding the suitcase with his left hand, but next shot his hands have switched to opposite positions. (00:19:40)
Continuity mistake: When Louise takes the jars of Javed's beetles and sneaks to her bedroom door, the door knob is at the left side of the door, but it should be at the right side as we've seen in previous shots. (00:12:15)
Continuity mistake: When Linda knocks on the door (Gene's bedroom) to say goodnight to the Samuels, there is a key hole on the door knob's backplate which is at the left side of the door, but when Linda leaves the room the key hole has vanished, but reappears later. Also later, this door knob/backplate switch to the opposite side of the door, on the right. (00:11:30)
Continuity mistake: After Louise sprays the pheromones onto Teddy's pillow, when it cuts to Linda knocking on Javed's door (Tina's bedroom) the door knob is on the left side, but the door opens the opposite way with the door knob on the right. (00:10:55)
Continuity mistake: When Ed and Nora Samuels arrive, Linda opens the front door at the right side (view from the outside facing in) and we see Jimmy Pesto's pizzeria across the street, but the problem is this door should have a door handle at the left side and open the opposite way. Then later, when the costumed characters show up, Linda again opens the front door at the right side, but then the door is opened properly in the opposite direction. (00:03:35)
Continuity mistake: When Linda opens the door to the first guest, in the shots facing Javed he has a bag with its strap crossed over his shoulder, but in two shots from behind Javed his bag is gone. (00:02:15)
Answer: It's a made up song for the show. It's a synth version of what the kids sang in Mr. Frond's video at the beginning of the episode. "Let's Swap Eyes."
Bishop73